This invention relates to an inertia locking mechanism for a vehicle occupant restraint belt retractor.
Vehicle occupant restraint belt retractors conventionally include a metal housing that rotatably supports a belt reel on which a restraint belt of either the lap or shoulder type is wound. A spring normally extends between the reel and the housing so as to bias the reel in a belt winding direction. At each of its ends, the reel normally includes an annular ratchet plate with teeth that face in the belt unwinding direction of rotation. Different types of locking members have been utilized in the past in order to engage the ratchet teeth of the reel to prevent the belt unwinding reel rotation.
Vehicle sensitive inertia belt locking mechanisms of the type the present invention relates to have also been known for some time. These locking mechanisms include an inertia member such as a pendulum that acts on a locking member in response to abrupt vehicle acceleration or deceleration to move the locking member to its reel locking position in engagement with the ratchet teeth on the end plates of the reel. Thus, the reel may be unwound to supply an increased length of belt at all times except during abrupt changes in its rate of movement.